The present invention relates to magnetic devices. More particularly, the present invention relates a shield design in a magnetic reader that reduces magnetic interactions between the shield, read element, and magnetic medium.
A magnetic reader retrieves magnetically encoded information that is stored on a magnetic medium. The magnetic reader is typically formed of several layers that include a top shield, a bottom shield, and a read element positioned between the top and bottom shields. A resistance of the read element fluctuates in response to magnetic fields emanating from the rotating magnetic medium when the read element is positioned proximate to the magnetic medium. The change in resistance of the read element can be detected by passing a sense current through the read element and measuring the voltage across the read element. External circuitry then converts the voltage information into an appropriate format for processing.
During a read operation, the top and bottom shields ensure that the read element reads only the information stored directly beneath it on the magnetic medium by absorbing stray fields emanating from adjacent tracks and transitions. However, the top and bottom shields, which are large soft magnetic structures, may focus external fields from the adjacent tracks and transitions. This effect is amplified by the vicinity of the soft underlayer of the magnetic medium. The stray fields may lead to a large erase field at the magnetic medium, which is largest at the offtrack edge of the shield due to the shield geometry.